For optimal conversion of pollutants contained in the exhaust gas of an internal combustion engine, namely hydrocarbons (HC) and carbon monoxide (CO) by means of oxidation and nitrogen oxides (NOx) by means of reduction, the objective is to maintain a lambda value of 1.0 for the air/fuel ratio supplied to an internal combustion engine. This lambda value is specified by a binary lambda probe, situated downstream from the catalyst, which operates as a pilot probe. However, the accuracy of the specification is influenced by various parameters such as aging of the lambda probe, the quality of the fuel supplied to the internal combustion engine, and the catalyst temperature. These deviations are not linear, however, and are therefore difficult to correct.
In light of the foregoing, the object of the present invention is to provide a method for checking the lambda value indicated by a binary lambda probe, in which the deviations between the indicated lambda value and the actual lambda value are determined, and on the basis thereof the lambda value indicated by the lambda probe may be corrected.